<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>isElement</title>
</head>
<body>
	<div id="test">aaa</div><!--这是一个注释节点-->
	<script>
		var isElement = function (el){
			return !!el && el.nodeType === 1;
		}
		var a = {
		   nodeType: 1
		}
		console.log(isElement(document.getElementById("test")));
		console.log(isElement(document.getElementById("test").nextSibling));
		console.log(isElement(a));
	</script>
</body>
</html>